Preheat oven to 350. In a small saucepan, melt a stick of the butter. Add the bananas and brown sugar and caramelize. Remove from heat and add the cinnamon and vanilla. Allow to cool slightly.
In a mixer, combine the remaining butter and white sugar. Add the egg and mix well. Add the cooled banana mixture, baking soda, and salt. Mix in the flour until just combined.
Spray 12 muffin liners with PAM and fill ⅔rds full. Bake for 18-20 minutes.
Recipe by Five Wooden Spoons at https://www.fivewoodenspoons.com/2013/06/17/bananas-foster-muffins/